1. FIELD OF THE INVENTION
This invention relates to macromolecular compounds useful, for example, for introducing chemical modifier groups into biologically active proteins and for fractionating proteins.
2. DESCRIPTION OF THE PRIOR ART
Biologically active proteins are expected to be useful as drugs. With the recent progress in gene recombination technology, it has become possible to produce biologically active proteins in large quantities. However, when a biologically active protein is administered to a living body, its effective biological activity is sometimes not attained because of the rapid elimination thereof from the living body or because of unsatisfactory delivery thereof to the target cells or tissues. Furthermore, administration to humans of biologically active proteins obtained from organisms other than human, such as other animals or microorganisms, may induce severe symptoms due to immune responses. Therefore, in using these proteins as drugs, technical developments are desired which will delay the rate of clearance of proteins, which will deliver proteins to specific cells or tissues, or which will reduce their immunogenicity (antigenicity), while maintaining their biological activities.
For the above reasons, various techniques for chemical modifications of proteins have been attempted.
In addition, attempts have also been made to discover macromolecular compounds usable in the separation and purification of proteins.